Three objects move along the x-axis. They start at the origin and move right. The threee graphs show the speeds of the three objects plotted against time. Calculate how far each object is from the origin at t=4.
If those gray lines are something different than the black ones this is wrong...but just add the total area between [0,1] he moves the area under the curve which is $\displaystyle 20\cdot{1}$....from [1,3] he goes nowhere since it is the area of a non-existant shape which is zero and from [3,4] the area is $\displaystyle 10\cdot{1}$...so $\displaystyle Distance_{total}=20\cdot{1}+10\cdot{1}=30$